(a) Field of the Invention
The present invention relates to a wideband code division access (W-CDMA) system. More specifically, the present invention relates to a demodulating device and method for W-CDMA base stations.
(b) Description of the Related Art
When implementing demodulators used for base stations of conventional CDMA systems using protocols such as the IS-95, resources including fingers and storage devices are previously established and allocated to the demodulators for each channel, and these channel components are assembled in parallel to allow for a plurality of channels together.
However, differing from the conventional communication systems, since the W-CDMA systems are required to concurrently provide services that have different resource sizes such as speech and image services, it is not effective to previously set the resources and allocate them.
Also, the demodulators for the conventional CDMA base stations use a non-coherent demodulation method that does not require channel estimation, but the third generation systems as well as the W-CDMA system use a coherent demodulation method, and accordingly, it is very important to improve performance of channel estimation when desiring to increase radio capacity of the system.
Regarding the W-CDMA standards, functions executed by the demodulator of a base station include data demodulation, transport format combination indicator (TFCI) decoding, feedback information (FBI) decoding, power control bits demodulating and signal-to-noise ratio (SNR) measurement.
However, they all have different time delay and reliability conditions. For example, the data demodulation and the TFCI decoding require high reliabilities when allowing a little time delay, the FBI decoding needs to have good reliability and not much time delay, and the power control bits demodulating require minimization of time delay when allowing somewhat low reliability.
Therefore, it is required for the demodulator used for the W-CDMA system to perform the decoding process differently depending on the time delay and reliability conditions.